Electro-magnetic device



(No Model.)

M'..G. CRANE.- ELEGTRO MAGNETIC DEVICE.

.No. 449,206. Pdtented Mar. 31, 1891.

' 1 iv N o I IQ 1 m O) E- N F w eg- I v a t l/ n Witness 8, f y nto? I I I 'I I I M G: aran/,

UNITED STATES MOSES G. CRANE, OF NEWTON, MASSACHUSETS.

PATENT Unmet.

ELECTRO-MAGNETIC DEVICE.

SPECIFICATION forming part of Letters Patent No. 449,206, dated March 31, 1891.

Application filed July 16, 1888.

To all 1071 0722, it may concern.-

Be it known that I, MOSES G. CRANE, of Newton, county of llliddlesex, State of Massachusetts, have invented an Improvement in Electro-Magnetic Devices, of which the following description, in connection with the accompanying drawings, is a specification, like letters and figures on the drawings representing like parts.

My invention relates mainly to the construction of an electro-magnet and armature and to the operating circuits for the same, the invention being shown embodied in an apparatus forstriking a gong or hell, although it is adapted for other uses. The construction of the magnet and armature is such that a very large amount of mechanical power is developed, so that the apparatus can be used for strikingaheavy blow on agong or for doing other mechanical work by the direct force of the magnet, instead of employing the magnet and armature merely to control a meehanical motor, as is usual where a considerable amount of power is required. In order to provide for a powerful attraction of the armature through a considerable range of angular movement, the magnet is, in accordance with this invention, made with enlarged poles, the surfaces of which presented to the armature are of considerable larger area than the sectional area of the core, of which the said poles form a magnetic continuation, being preferably made integral therewith, although they may in some cases be made of separate pieces properly fastened to the cores of the magnet. In order to prevent strain of the frame-work of the apparatus, the armature is pivoted directly upon the said enlarged poleextensions, which have suitable pivoted lugs that are engaged'with corresponding pivotlugs on the armature by a suitable pintle, constituting a hinged joint, one member of which is magnetically insulated from the other, so as to prevent a direct magnetic c011- nection between the poles of the magnet. The coils of the magnet are shown as included in two distinct circuits, each containing a battery or other source of electrical energy, and one of which, called for distinction the main circuit, is controlled by appliances external to and unaffected by the magnet and its armature, while the other, called for distinction Serial No. 280,041. (No model.)

the local circuit, contains a circuit-closer that is operated by the armature in its movement between the posit-ions most remote from and nearest to the poles of the magnet. The armature and its retractor are so adjusted that the armature normally remains when there is no current passing through its magnet-coils from either circuit in an intermediate position between its extreme backward position most remote from the poles and its extreme forward position nearest the poles of the magnet, and the circuit-closer of the local circuit is so constructed as to be closed only when the armature passes beyond the said normal position and arrives at or near its eX- treme backward position. By this construction and arrangement the current in the main circuit when applied has only to attract the armature from its intermediate position, and when the armature is released by the removal of such current in the main circuit it passes byits momentum beyond its normal intersition, so that it closes the local circuit,'which again causes the armature to be attracted up to the poles of its magnet, the current in the local circuit being of sutlicient strength to give the armature the required power of movement.

Figure l is a side elevation of an electromagnetic device embodying this invention, the circuits being shown in diagram; and Fig. 2, a plan view of a portion of the magnet and its armature, showing the construction of the hinge-joint between the armature and mag net'poles.

The apparatus comprises an electro-magnet a and armature I) therefor, which armature is shown in this instance as provided with an arm b carrying a bell-hammer biwhich, when the armature is attracted, strikes a blow on i the gong or bell, a portion of which is shown at a. The cores of the magnet a have polar extensions to, which may be made integral with the core-pieces or fastened thereto, and which have a polar surface opposite the armature b of considerably greater area than the cross-sectional area of the cores, and thus act more powerfully on the armature than it the extremity of the cores themselves constituted the poles of the armature.

In order to bring the pivotal axis Z) of the mediate position to its extreme backward p0 armature near the poles, and at the same time to relieve the frame-work of the apparatus from being strained by the force of attraction exerted between the magnet and armaturc, the said armature is pivoted or hinged directly upon the poles of the magnet, which are provided with hinged lugs (1. which may be and preferably are cast integral with the pole-pieces. The armature has connected with it corresponding lugs c, which are of brass or other non-magnetic material, and are pivotally connected with the lugs a by pintles (Z, thus making a direct hinged joint between the armature and the magnet-poles, as shown in Fig. 2, but preventing magnetic continuity between the poles except when the armature is in contact with the faces thereof. The armature is so arranged, as shown in Fig. 1, as to be retracted some distance fromthe poles of the magnet by the action of gravity, and it may in addition have a retractingspring f, and it is so adjusted that normally when wholly unaffected by the attraction of the magnet it remains in an intermediate position between the position nearest to and most remote from the poles of the magnet, which positions will be called for brevity its forward and backward positions, respectively.

The coils of the magnetare included in two separate circuits, one of which is shown as connected with the ground at 2 and includes a battery B, from which the circuit is extended to one terminal 3 of the magnet, the other terminal 4 of which is connected by conductor 5 with a circuit-controlling instrument or current-interrupter 0, (shown as a break-wheel,) the normal position of which causes the said maiii circuit 2 i 5 to be opened, but which when rotated produces a definite series of' closures and breaks in the said circuit. The terminals 3 a of themagnet 64 are also connected with a local circuit 6 7 8, including a battery B and a circuitcloser 7t 2', the member h of which is pivoted at h in position to be operated by a projee tion 7L on the arm connected with the armature. The said movable member h of the circuit-closer has cam projections 71 7f, which are engaged by the projection 7r when the armature arrives at its extreme backward and forward positions, the engagement with the projection 7L2 causing the circuit-closer h 1' to be closed and the magnetato be consequently energized by the battery B when the armature arrives at its extreme backward position. Such energizing of the magnet a causes .the armature to be attracted, and in coming to its forward position it opens the circuit-closer h 11 by the engagement of the projections 71. 771 thus permitting the armature to be again retracted, so that if the magnet were under control of the local circuit alone, including the battery B, the armature would continue to vibrate between its extreme positions as long as the said battery supplied sufficient current, provided that the armature was once moved back from its normal position,so as to once close the circuit-closer h i. The construction of the circuit-closer hi in the local circuit controlled by the armature as a switch, as shown, is desirable when the armature is intended to act with great power, as it retains the local circuit closed during nearly the entire forward stroke of the armature; but it is obvious that other well-known kinds of circuit closers-such as commonly employed with vibrating armaturesmight be used,the essential feature of this part of the invention being that the said circuit-closer 1 s open when the armature is in the normal position, with the magnet wholly demagnetized, and is closed by the movement of thesaid armature back past the said normal position, which takes place by the momentum of the armature when released from its extreme forward position.

In order to cause the armature to move to its extreme backward position, and thus call the local circuit into operation, and also to control the operation so that the armature may make definite movements at definite times instead of continuing to vibrate, as it would if acted upon by the local circuit alone, the main circuit 2 3 4 5 is operated, as will now be described. The current in the main circuit need only be sufficient to attract the armature from its intermediate or normal position, (shown in Fig. 1,) which is done when the said circuit is closed by the break-wheel c or other circuit-closing instrument therein. Then if the main circuit be broken the armature will fall back, and by its momentum will pass to the extreme backward position and close the local circuit, the current of which will then attract the armature and supply the current for making the efiective forward stroke.

In order to retain the armature under control of the main-circuit the breaks in the said circuit or interruptions in the current thereof are of about the same or slightly shorter duration than the time required for making a complete backward and forward stroke of the armature, so that after the armature has finished its forward stroke it will be held by the attraction of the main current and will not make a second stroke until there is another break in the main circuit. The armature will thus continue to respond to the breaks in the main circuit, although it is actuated IIO mainly or wholly by the current in the local circuit, and it will thus strike out a signal corresponding to the number of the notches in the break-wheel 0. As the said breakwheel will finally come to rest with the main circuit open,the armature will be finally left under control of the local circuit alone, and

will therefore continue to vibrate after the circuit changes in the main circuit cease. It will consequently have to be brought to its normal position by some other means than those thus far described. This maybe effected by means of a switch in the local cir cuit, which when open,after the main circuit has been left open, will cause the magnet (t to remain wholly demagnetized, and thus permit the armature to come to its normal intermediate position, after which the circuitcloser 72 2', if of the construction shown, may be opened by hand and the switch S again closed, thus leaving the apparatus in the normal condition, (shown in Fig. 1,) ready to respond to another signal in the main circuit. By this arrangement it will be i seen that the magnet and its armature is controlled as to its operation by the main circuit, and after being once set in operation may remain in control of the main circuit as long as required, but is finally left under control of the local circuit and cannot be restored to its normal position by any operation of the main circuit alone.

It is obvious that instead of providing for a definite series of operations under control of the main circuit the latter might be employed merely to set theinstrument in operation, merely closing and breaking the said main circuit a single time, as by a key K, and the operation might be stopped merely by arresting the armature while making its back-stroke before the circuit-closer h 2' was closed by it, which might be done by hand.

In another application, Serial No. 270,045, filed April 9, 1888, patented September a, 1888, No. 388,SS6,I have shown and described an electro-magnet and armature operated by a main and local circuit, the former of which controls and the latter of which actuates the apparatus; but in said apparatus there is also a mechanical device which automatically takes the armature out of control of the local circuit after each stroke is made, and the re tractive forces on said armature are such as to carry it to and retain it in its extreme backward position when left free to move with the magnet demagnetized.

Ido not in the present application broadly claim a magnet and main and local circuits therefor with circuit -changing devices included in said circuits by which the magnet is controlled by the main circuit and is actuated mainly by the local circuit.

I claimand its armature pivoted to vibrate back and forth before the poles of the said magnet and normally when the said magnet is demagnet ized, remaining in an intermediate position between its extreme forward and backward positions, combined with a main circuit through the said magnet and a local circuit through the said magnet, and a circuit-closer in said local circuit, arranged with relation to said armature as described, whereby the said circuit-closer in the local circuit remains open when the armature is in its normal intermediate position and is closed when the armature moves backward beyond said normal intermediate posit-ion, substantially as and for the purpose described.

- 2. The combination of an electro-magnet and its armature normally remaining when unattracted in an intermediate position between its nearest and most remote positions with relation to the magnet-poles, and a local circuit through said magnet and circuitcloser therein, combined with and arranged with relation to said armature as describednamely, being open when said armature is in its normal intermediate position and closed when said armature moves backward beyond said intermediate position, and a main circuit through said magnet and current-inter rupter therein, the interruptions produced by which occupy a time substantially equal to or less than the time occupied by a complete to-and-fro vibration of the armature, substantially as and for the purpose set forth.

The combination of an electro-magnet with an armature pivoted to vibrate back and forth before the poles of said magnet and adj usted to remain in an intermediate position between its extreme forward and backward positions when unattracted, and an electric circuit through said magnet, and a circuitcloser therein arranged with relation to the said armature as described, being engaged and closed by said armature when it moves backward beyond its normal position of rest, substantially as described.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

MOSES G. CRANE.

Witnesses:

J os. P. LIvnRMoRn, M. E. HILL. 

